Development of Time-spectroscopy System for Observing Internal-conversion Electrons at Rare Nuclear Excitation Phenomena

in fy 1997,一个电子分析工具，用于time-spectroscopy was设计和解释。cylindrical-mirror type.下一个年份，some avalanche photodiodes (APDs) were tested at beamline BL14A of the Photon Factory. One设备that had a thin SiO D2 layer was chosen as the electron detector for the analyzer. Until theend of FY1998我们不能报告这个项目的结果这个项目due to the delay of improving the electron analyzerand due to no chances of experiments at Spring-8. However, in April and May of 1999，we were able to the experiments under a new project of the SPring-8. In the experiments，we successfully observed the nuclear excitation by electron transition in 197Auinternal-conversion electrons emitted from excited nuclei directly detected by the APD devicewithout the electron analyzer.这个方法是利用一个大的效率conversion electrons. The observed NEET probability was close to The calculated value （e.v.t kalya）jetp 78239 (1994)),though smaller by three orders of magnitude than the previous experimental value (h.f ioka et al.，z.p oys . A315, 121(1984))。

In FY1997, an electron analyzer for time-spectroscopy was designed and assembled. The analyzer was cylindrical-mirror type. Next year, some avalanche photodiodes (APDs) were tested at beamline BL14A of the Photon Factory. One device that had a thin SiOィイD22ィエD2 layer was chosen as the electron detector for the analyzer. Until the end of FY1998, we could not report the results of this project due to the delay of improving the electron analyzer and due to no chances of experiments at Spring-8. However, in April and May of 1999, we were able to execute the experiments under a new project of the SPring-8. In the experiments, we successfully observed the nuclear excitation by electron transition (NEET) in 197Au. The internal-conversion electrons emitted from excited nuclei were directly detected by the APD device without the electron analyzer. This method was adopted for taking a larger efficiency of the conversion electrons. The observed NEET probability was close to the calculated value (E.V.Tkalya, JETP 78,239(1994)), though smaller by three orders of magnitude than the previous experimental value (H.Fujioka et al., Z.Phys. A315, 121 (1984)).